1. Field of Invention
The present invention relates to drilling equipment and, more particularly, is directed toward rock boring tools.
2. Description of the Prior Art
Generally, rotary conical roller bits for reaming pilot holes drilled in rock include rotary cutters that are supported in fixed bearings mounted to a frame. The rotary cutters are moved over the surface being cut at substantially right angles to the plane thereof. When roller bits arrive at hard formations, much difficulty is experienced. Advancement of the bit is very slow and the wear on the cutting edges is excessive. The stress on the roller bit is such as to cause a misalignment of the rotary cutters and excessive wear on the bearings which results in premature failure. In addition, a build up of pressure from flushing fluids and cuttings results in contaminants entering the bearings and causing premature failure. A need has arisen for improvements in rotary conical roller bits.